1. Field
The subject matter disclosed herein relates to mobile electronic devices, and, more particularly, to methods, apparatuses, and articles of manufacture that may be used to estimate a location of a mobile device using, for example, a radio heatmap of an indoor area.
2. Information
The global positioning system (GPS) and other like satellite positioning systems (SPSs) have enabled navigation services for mobile handsets in many types of outdoor environments. However, since satellite signals may not be reliably received and/or acquired in some indoor environments, different techniques may be employed to enable indoor navigation services. For example, a mobile device may typically obtain an estimated location by measuring ranges to three or more wireless access points that may be positioned at known locations. Such ranges may be measured, for example, by obtaining a media access control identification (MAC ID) address from signals acquired from such access points and measuring one or more characteristics of received signals. In one example, round trip signal delay may be measured between a mobile device and a wireless access point, which may be used to compute an estimated location of the mobile device.
However, in some indoor environments, multipath interference may occur if signals propagate between mobile devices and wireless access points along direct and indirect paths. In such instances, transmitted signals arriving at a mobile device by way of direct and indirect paths may interfere with one another, thus giving rise to degradations in capability of the mobile device to compute an estimated location. In such instances, round-trip signal delay measurements may be complemented through a use of one or more radio heatmaps, which may be utilized in place of, or in addition to, round trip signal delay measurements. Radio heatmaps may be generated with respect to individual wireless access points and may permit a mobile device to estimate its location within an indoor area by comparing received signal strength with expected signal strengths from the radio heatmap. However, in some instances, radio heatmaps may be generated under conditions that, from time to time, may fluctuate. Such fluctuations may negatively impact accuracy of radio heatmaps and thus bring about errors in position estimation of mobile devices.